Amgen has had a torrid time of late in the USA and has now been hit by some news on this side of the Atlantic as a panel attached to European regulators have rejected its bid to market the cancer drug Vectibix.

The European Medicines Agency’s Committee for Medicinal Products for Human Use has adopted a negative opinion for Amgen's marketing authorisation application for Vectibix (panitumumab) for patients with metastatic colorectal cancer who have failed chemotherapy. The CHMP criticised the design of the main 463-patient study that Amgen presented and claimed that in the first few weeks of the study, many of the patients originally receiving best supportive care alone started to receive the drug after their disease had got worse, “making it difficult to compare the effects of Vectibix and best supportive care alone”.

The agency’s panel added that Vectibix “only had a very small effect in increasing the time until the disease got worse or the patient died, in comparison with best supportive care”, saying that studies also showed that patients receiving the drug had increases in side effects. These included skin reactions, “which resulted in poorer quality of life in the patients reporting them”.

Amgen quickly responded by lodging an appeal against the CHMP’s opinion and said that it is confident “the available data demonstrates that Vectibix improves progression-free survival for colorectal cancer patients who have progressed on, or following fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens.

Vectibix is the first fully human IgG2 monoclonal antibody that targets the epidermal growth factor receptor, and it was approved by the US Food and Drug Administration in September 2006. However it suffered a setback earlier this year when Amgen discontinued a late-stage trial of Vectibix which was designed to prove the drug's efficacy as part of a potential first-line treatment for patients with colorectal cancer.

That news saw analysts cut their predictions for Vectibix sales, which reached $59 million in the first quarter, and the drug is facing stiff competition from ImClone System's Erbitux (cetuximab), which is marketed in Europe by Merck KGaA.

Amgen will probably be glad to see the back of May. Earlier this month, an FDA oncology advisory committee recommended further strengthening of the warning labels on its erythropoiesis-stimulating agents, Aranesp (darbepoetin alfa) and Epogen (epoetin alfa), and that was followed by the US government's health insurers announcing plans to restrict coverage on the two anaemia drugs.